Health professionals who treat people with psychiatric problems often overlook their patients' smoking habits, assuming it's best to tackle depression, anxiety or substance abuse problems first. However, new research at Washington University School of Medicine in St. Louis shows that people who struggle with mood problems or addiction can safely quit smoking and that kicking the habit is associated with improved mental health. The study is published online in the journal Psychological Medicine.

"Clinicians tend to treat the depression, alcohol dependence or drug problem first and allow patients to 'self-medicate' with cigarettes if necessary," said lead investigator Patricia A. Cavazos-Rehg, PhD. "The assumption is that psychiatric problems are more challenging to treat and that quitting smoking may interfere with treatment."

But in the study, Cavazos-Rehg, an assistant professor of psychiatry, found that quitting or significantly cutting back on cigarette smoking was linked to improved mental health outcomes. Quitting altogether or reducing by half the number of cigarettes smoked daily was associated with lower risk for mood disorders like depression, as well as a lower likelihood of alcohol and drug problems.

"We don't know if their mental health improves first and then they are more motivated to quit smoking or if quitting smoking leads to an improvement in mental health," Cavazos-Rehg said. "But either way, our findings show a strong link between quitting and a better psychiatric outlook."

In addition, she believes the serious health risks associated with smoking make it important for doctors to work with their patients to quit, regardless of other psychiatric problems.

"About half of all smokers die from emphysema, cancer or other problems related to smoking, so we need to remember that as complicated as it can be to treat mental health issues, smoking cigarettes also causes very serious illnesses that can lead to death," she explained.

Cavazos-Rehg and her team analyzed questionnaires gathered as part of the National Epidemiologic Study on Alcohol and Related Conditions. In the early 2000s, just under 35,000 people were surveyed. As part of the study, they answered questions about drinking, smoking and mental health in two interviews conducted three years apart.

The researchers focused on data from 4,800 daily smokers. Those who had addiction or other psychiatric problems at the time of the first survey were less likely to have those same problems three years later if they had quit smoking. And those who hadn't had psychiatric problems at the initial survey were less likely to develop those problems later if they already had quit.

At the time of the first interview, about 40 percent of daily smokers suffered mood or anxiety disorders or had a history of these problems. In addition, about 50 percent of daily smokers had alcohol problems, and some 24 percent had drug problems.

Forty-two percent of those who had continued smoking during the years between the two surveys suffered mood disorders, compared with 29 percent of those who quit smoking. Alcohol problems affected 18 percent of those who had quit smoking versus 28 percent who had continued smoking. And drug abuse problems affected only 5 percent of those who had quit smoking compared with 16 percent of those who had continued smoking.

"We really need to spread the word and encourage doctors and patients to tackle these problems," Cavazos-Rehg said. "When a patient is ready to focus on other mental health issues, it may be an ideal time to address smoking cessation, too."